Is suicide bombing not sectarian violence?

On Friday night while driving around Boston I was listening to NPR, and Terry Gross (I think) interviewed a BBC reporter in Baghdad to discuss the horrific bombings in which two women with Down syndrome were used to detonate explosives among dozens of innocent Iraqis. Terry talked about the changing tactics by insurgent groups. Terry said that suicide bombings have not killed nearly as many people as the sectarian violence has. I asked myself (I have asked this before) if suicide bombings are not sectarian violence. Is suicide bombing not the worst form of sectarian violence, since the victims always include women and children? Or does suicide bombing not fit the definition of "sectarian violence" because the victims may also be Sunni Arabs? Certainly there were Sunni Arabs (CHILDREN) among the dead and injured. Or is it sectarian violence only if the Shia militias strike back, killing innocent Sunni Arabs? No, I still contend that this is an example of sectarian violence. I still wonder what people are thinking when they say that the sectarian violence started after the bombing of the Askariya shrine.

PS: I just realized that the bombings at the pet markets were not suicide bombings - nobody actually committed suicide! I guess this was not clear at the time Terry did the interview Friday night. Still it is an example of sectarian violence, in my opinion, and so are most suicide bombings in Iraq.